Method of making cellular clay products



Patented Nov. 13, 1934 UNITED STATES METHOD OF MAKllN G CELLULAR CLAYPRODUCTS Clarence S. Matheny, Haydenville, Ohio, assignor to NationalFireproofing Corporation, Pittsburgh, Pa., a corporation of PennsylvaniaNo Drawing. Application October 7, 1932,

Serial No. 636,683

6 Claims.

This invention relates to a method of making cellular clay products ofthe character disclosed in copending applications Serial Nos. 453,395filed May 17, 1930 which has become Patent 1,897,667 and 454,796 filedMay 22, 1930, and it is among the objects of the invention to employ aprocess for controlling the size of the cell structures in accordancewith the necessity for producing specific characteristics in the productfor particular applications in their use, and the invention furthermakes provision for weakening the walls of the cells when the cellularstructure is designed to be employed for acoustic correction purposes.

As set forth in the above mentioned copending applications, the cellularclay product is formed by compounding clay, dolomite and gypsum, andmixing the powderous ingredients with an acid solution which generates agas that produces the cellularity in the finished product, the size ofthe cells being controlled largely by the quantity of gypsum employed toefiect quick setting of the liquid mixture. The product is of lightweight and is fire-resistant which makes it available for use as arefractory insulator in heating structures, and generally as heatinsulation for building purposes.

The present invention has to do with a process for controlling the sizeof the cells and the density of the cell walls to render the productmore eificient in its application for the purposes stated.

The material is a fired clay product of high cellularity. The weight ofthe material varies with the degree of cellularity and the strength ofthe light-weight material can be controlled by the size of the cells,the percentage of cellularity, and the degree of burning.

In accordance with the present invention, the cellular clay is producedby feeding powderous clay, gypsum and dolomite in suitable proportionsto a blunger containing a solution of sulphuric or hydrochloric acid andblunged until a smooth creamy consistency is obtained. The creamy slipis then poured into molds where the chemical reaction between thevarious ingredients continues for some minutes which causes the mixtureto bloat, forming the cells. By adding a pasty substance, such as flour,to the dry ingredients, the viscosity of the slip is increased, andbecause of the more plastic proportions of the flour, a film is producedaround each dolomite particle so that when the gases are producedthrough chemical action of the acid solution with the dolomiteparticles, such gases will be prevented from uniting whereby they'areretained as individual cells of relatively small sizlfl The size of thecells can be varied in accord-1 ance with the proportion of flouremployedin the mixture, and after the so' -calledbloa'ting of theproduct, it will set rapidly on ,accounti'of the gypsum employed in themixture,and may be then removed from the blunger and is ready forfiring.

Instead of employing the fiour to obtain a 5 pasty consistency forproducing the film around the dolomite particles, it isobvious that theviscosity of the slip may beincreased by the employment of ingredientsother than flour, such as finely ground clay. l

The essential step in the practice of the invention is the inclusion ofan ingredient that will produce a doughy consistency which retards thecell growth, and such doughy substance will, to:- gether with the claybody, constitute the cell walls. The doughy consistency retards the cellgrowth by preventingthe gases of two dolomite cells from uniting to forma large cell, and the smaller cell structures obviously have a thickerwall than the large cells so that the resultant 0 product is especiallyadapted for use as insulating material since the loss of heat byradiation will be greatly retarded by the increased resistance of thelarger number of cells in the structure.

When it is desirable to produce a highly porous 5 or weakened cell wall,the fiour or its equivalent is omitted and bran is utilized in the clay,dolomite and gypsum mixture with the acid solution. The flaky bran willcinder and burn out of the clay body when the mixed product is subjectedto the firing operation, leaving the wall structure of the cellsperforated and permitting the cells to communicate with each other. Aproduct of such broken or weakened cells is especially applicable foruse for acoustic correction purposes 5 in theatres, radio studios, andthe like, since it will only partially weaken the cellular structurewhich is of sufiicient strength to be employed in walls or ceilings forthe purposes mentioned.

It has been found that the flour or its equivalent can be used in thefollowing proportions: With one hundred pounds of clay, ground to passthrough a twenty-mesh sieve while dry; ten pounds of gypsum and threepounds of dolomite, sixty-mesh; from one ounce to 16 ounces of fiour maybe employed to control the cell size as desired. These ingredients aremixed with an acid solution of from to 1% commercial sulphuric acidH2304 and blunged to a smooth creamy consistency and then poured intomolds. If in) flour in excess of the stipulated quantity is employed, itwill cause a weakening of the cell walls by the burning of the productwhich may be desirable in some instances where it is necesssary toproduce a structure of small cells with perforated walls, but it isundesirable when the product is to be used for insulating purposes.

It is, of course, obvious to those skilled in the art that theproportion of the ingredients herein specified or the manner ofcompounding them may be varied within the spirit of this invention.

I claim as my invention:

1. The process of manufacturing a fire-resisting cellular clay productcomprising the steps of producing a fluid clay slip by compounding clay,dolomite and gypsum with an acid solution, releasing a gas by chemicalinteraction of the dolomite and acid in said slip while the latter is ina formative condition, introducing regulated quantities of a pastysubstance to confine the chemical interaction to unit particles of thedolomite whereby relatively small cells are formed, and subsequentlyheat treating the dry cellular mass to harden the product.

' '2. The process of manufacturing a'fire-resisting cellular productcomprising the steps of producing a fluid clay slip by compounding clay,dolomite and gypsum with an acid solution, releasing the gas by chemicalinteraction in said slip by an interaction of the acid with the dolomitepresent in the mixture, and introducing a pasty substance to confine theinteraction of the acid with unit particles of the dolomite whereby theresultant cells are of relatively small size.

3. The process of manufacturing a fire-resisting, cellular productcomprising the steps of producing a fluid clay slip by compounding clay,dolomite and gypsum, then bloating said mixture by the interaction of anacid solution with the dolomite particles, and introducing regulatedquantities of grain flour to produce a film around the dolomiteparticles to prevent the uniting of the gases generated by saidparticles into relatively large cells.

4. The process of manufacturing a fire-resisting cellular productcomprising the steps of producing a fluid clay slip by compounding clay,dolomite and gypsum, adding a combustible pasty substance to saidmixture, bloating said mixture by the interaction of an acid solutionwith the dolomite present in the mixture, and subsequently heat treatingthe dry cellular mass to harden the cellular product.

5. The process of manufacturing a fire-resisting cellular productcomprising the steps of producing a fluid slip from clay, dolomite andan acid solution, releasing a gas by chemical interaction of dolomitewith the acid in said slip while the latter is in a formative condition,regulating the expansion of gases in said slip by introducing regulatedquantities ofgypsum therein, introducing a pasty substance in said slipto confine the formation of the gases in relatively small cells, andsubsequently heat treating the dry cellular 100 mass to harden thecellular product.

6. The process of manufacturing a fire-resisting cellular productcomprising the steps of producing a fluid slip from clay, dolomite, and.an acid solution, releasing a gas by chemical inter- 105 action ofdolomite with the acid in said slip while the latter is in a formativecondition, regulating the expansion of gases in said slip by introducinga pasty substance to confine the formation of the gases in relativelysmall cells, and'subsequently 110 heat treating the dry cellular mass toharden the cellular product.

CLARENCE S. MATHENY..

